DE102015223675B4 - Time-of-flight sensor for an optical range finder - Google Patents

Abstract

Time-of-flight sensor (22) for an optical range finder (1), with a time-of-flight pixel (23) for demodulating a received modulated light signal (Sp2), the light-time-of-flight pixel (23) having a plurality of reception areas (23.n) arranged in a matrix with at least one readout finger (Dan , Dbn) for an A and B channel, and a respective readout finger (Dan, Dbn) has at least one integration node (Da, Db) designed as a diode node, the light transit time pixel (23) having an integrator (410) for integrating the has charges detected at the diode nodes (Da, Db), and the readout fingers (Dan, Dbn) of a channel (A, B) are connected individually or in groups to an input of a switch (SA1..n, SB1..n), the switches (SA1..n) for the readout fingers (Dan) of the A channel at a first output of the switch (SA1..n) with an A channel input of the integrator (410) and the switches (SB1..n) for readout fingers (Dbn) of the B-channel at a first output of the switch (SB1..n) with a B-channel input of the integrator (410) and that the switches (SA1..n, SB1..n) at a second output are connected to an input of a discard node (450), the time-of-flight sensor (22) being designed in such a way that, during operation, the changeover switches (SA1..n, SB1..n) connect the readout fingers (Dan, Dbn) either to an input of the integrator (410) or to an input of the discarding node (450), a further input of the discarding node (450) having a reference voltage (Vref) which is that at the further A and B channel inputs of the integrator (410) corresponds to the applied voltage, the receiving areas (23.n) whose readout fingers (Dan, Dbn) are connected to the integrator (410) forming active receive areas (23.n), and the readout fingers (Dan, Dbn) connected in this way to the integrator (410) that the geometry of the combined active receiving areas (23.n) takes into account a distance-dependent change in location and size of the light spot (50).

Description

The invention relates to a time-of-flight sensor for an optical range finder and a range finder according to the species of the independent claims.

Light propagation time measuring systems that not only determine distances directly from the light propagation time, but in particular all light propagation time or 3D-TOF measuring systems that obtain propagation time information from the phase shift of emitted and received radiation are particularly suitable as optical rangefinders. PMD sensors with photomixing detectors (PMD) are particularly suitable as time-of-flight sensors or receiving elements, such as those described in the applications EP 1 777 747 A1 , U.S. 6,587,186 B2 and also DE 197 04 496 A1 described and can be obtained, for example, from the company "ifm electronic gmbh" as an O3D camera or as optical distance sensors O1D, OSD, OID.

Furthermore, from the EP 1 332 594 A2 a PMD sensor configuration is known in which no modulation gates are used to separate the photonically generated charges, but the separation takes place exclusively via the accumulation gates or integration nodes themselves.

From the DE 102004016626 A1 and DE 102005056774 A1 Also known are so-called SBI (suppressed background illumination) circuits, which expand the dynamics of a pixel by suppressing background light for each pixel.

From the DE 10 2004 037 137 A1 a line-shaped PMD sensor is basically known. In one exemplary embodiment, it is proposed to combine two TOF elements into one pixel and to operate them phase-shifted by 90°, so that both phase positions can be detected simultaneously in one pixel.

The DE 10 2012 223 298 A1 deals with the structure of a pixel with a non-linear characteristic. For this purpose, the readout nodes of the pixel are connected to a compression transistor, via which the course of the charge integration can be influenced by applying a gate voltage.

The DE 10 2009 029 364 A1 shows a measuring device for optical distance measurement, in which the detection surface has a large number of pixels, via which distance data are determined with the aid of an evaluation device. The size of the detection areas can be adjusted to improve the signal-to-noise ratio.

The DE 10 2005 062 320 A1 deals with an optoelectronic device with a transmitter and a receiver with several receiving elements, which detect objects in a predetermined distance range according to the triangulation principle.

The DE 10 2006 049 905 A1 discloses an optoelectronic sensor having an emitter for emitting light into a surveillance area and a detector for detecting light reflected from a target object. The active surface of the detector can be adjusted in position and shape to the received light spot.

The object of the invention is to improve an optical range finder with regard to error accuracy and/or simpler adjustment of the optical system.

The object is solved in an advantageous manner by the distance meter according to the invention.

A time-of-flight sensor for an optical range finder is advantageously provided, with a time-of-flight pixel for demodulating a received modulated light signal, the light-time-of-flight pixel having a plurality of reception areas arranged in a matrix with at least one readout finger for an A and B channel, and each readout finger having at least one diode node , wherein the time-of-flight pixel has an integrator for integrating the charges detected at the diode nodes, and the readout fingers of a channel are connected individually or in groups to an input of a switch, the switches for readout fingers of the A channel being connected to a first output of the switch with a A- channel input of the integrator
and the switches for readout fingers of the B-channel at a first output of the switch to a B-channel input of the integrator
and that the changeover switches are connected at a second output to an input of a discard node, the time-of-flight sensor being designed in such a way that during operation the changeover switches connect the readout fingers either to an input of the integrator or to an input of the discard node, the reception areas whose readout fingers are connected to the integrator, form active reception areas, and the readout fingers are connected to the integrator in such a way that the geometry of the combined active reception areas takes into account a distance-dependent change in location and size of the light spot.

This procedure advantageously makes it possible to optimally adapt the geometry of the time-of-flight pixel to the respective measurement requirements by hiding areas that are not required. By the Switching over the areas not illuminated by the useful light from the integrator to the discard node, interfering signal contributions are kept away from the integration. In particular, this improves the signal-to-noise ratio and the accuracy of the range finder. In particular, the shot noise can be reduced in this way, for example.

It is also advantageously provided that the geometry of the active reception areas connected to the integrator and combined is funnel-shaped.

With this design, the receiving area can advantageously be adapted to the distance-dependent change in size and location of the light spot.

Furthermore, it is advantageous to switch over the reception areas or the readout fingers to the integrator or reject node as a function of a determined distance value and/or the strength of the received signal.

This procedure allows the reception areas to be dynamically adapted to the respective measurement situation and the light spot size, position and/or signal strength that may change depending on the object distance. For example, a reflection from a triple mirror can cause the signal strength to become so high that the sensor becomes saturated and can no longer be evaluated. Due to the adaptation of the reception areas according to the invention, part of the photosensitive surface can be masked out and the dynamic range of the sensor can thus be increased.

In a further embodiment, it is provided that the receiving element or the time-of-flight sensor is arranged in such a way that when the distance of the object changes, the light spot moves in the direction of a longitudinal axis of a receiving area.

This arrangement makes it possible, particularly in the case of so-called two-eyed systems, i.e. systems in which the transmitter and receiver are arranged at a distance from one another, to take into account the geometric change in position of the light spot due to a so-called triangulation effect.

It is particularly advantageous to configure the reject node in such a way that the impedance and/or input voltage of the reject node corresponds to the impedance and/or input voltage of the integrator. This procedure ensures that no potential shifts occur on the pixel as a result of switching between the integrator and discard nodes.

It is particularly advantageous to equip an optical range finder with an aforementioned time-of-flight sensor.

The invention is explained in more detail below using exemplary embodiments with reference to the drawings.

• 1 schematisch das grundlegende Prinzip eines optischen Entfernungsmessers,
• 2 schematisch ein PMD-Lichtlaufzeitpixel,
• 3 ein singuläres Lichtlaufzeitpixel mit einem einzigen Empfangsbereich,
• 4 ein erfindungsgemäßes Lichtlaufzeitpixel mit mehreren Empfangsbereichen,
• 5 ein Pixel mit ausgeblendeten Empfangsbereichen,
• 6 ein Pixel gemäß 5 mit einem verschobenen Nutzlicht-Empfangsbereich,
• 7 einen Querschnitt eines PMD-Lichtlaufzeitpixels mit Diodenknoten,
• 8 eine Aufsicht auf ein Lichtlaufzeitpixel gemäß 7,
• 9 ein Lichtlaufzeitpixel mit durchlaufender Struktur,
• 10 eine erfindungsgemäße Ausleseschaltung,
• 11 ein Timing-Diagramm für eine erfindungsgemäße Schaltung,
• 12 ein erfindungsgemäßes Pixel mit Umschaltern,
• 13 ein optischer Entfernungsmesser mit seitlicher Beleuchtungsquelle,
• 14 ein Pixel gemäß 5 mit einem ortsveränderlichen Lichtspot,
• 15 ein optischer Entfernungsmesser mit zentraler Beleuchtungsquelle,
• 16 einen Lichtlaufzeitsensor mit einer trichterförmigen Empfangsbereichs-Matrix,
• 17 einen Lichtlaufzeitsensor gemäß 16 mit einem ausgeblendeten Fernbereich,
• 18 einen Lichtlaufzeitsensor gemäß 16 mit einem ausgeblendeten Nahbereich.

Show it:

• 1 schematically the basic principle of an optical range finder,
• 2 schematically a PMD time-of-flight pixel,
• 3 a singular time-of-flight pixel with a single receiving area,
• 4 a time-of-flight pixel according to the invention with a plurality of reception areas,
• 5 a pixel with hidden reception areas,
• 6 one pixel according to 5 with a shifted useful light reception area,
• 7 a cross-section of a PMD time-of-flight pixel with diode nodes,
• 8th a top view of a time-of-flight pixel according to FIG 7 ,
• 9 a time-of-flight pixel with a continuous structure,
• 10 a readout circuit according to the invention,
• 11 a timing diagram for a circuit according to the invention,
• 12 a pixel according to the invention with switches,
• 13 an optical range finder with a side illumination source,
• 14 one pixel according to 5 with a portable light spot,
• 15 an optical range finder with a central illumination source,
• 16 a time-of-flight sensor with a funnel-shaped receiving area matrix,
• 17 according to a time-of-flight sensor 16 with a blanked far area,
• 18 according to a time-of-flight sensor 16 with a blanked out close range.

In the following description of the preferred embodiments, designate equal che reference symbols same or comparable components.

1 shows an optical range finder, as for example from the DE 197 04 496 A1 is known.

The optical range finder 1 comprises a transmitter unit or transmitter 10 with a light source 12 and a transmitter optics 15 and a receiver 20 with a receiver optics 25 and a receiver element 22. The receiver element 22 is preferably designed as a PMD sensor.

The measuring principle of this arrangement is based on the fact that the propagation time and thus the distance covered by the received light can be determined based on the phase shift of the emitted and received light. For this purpose, the light source 12 and the receiving element 22 are acted upon by a modulator 30 together with a specific modulation frequency M(p1) with a first phase position p1. The light source 12 emits an amplitude-modulated signal S(p1) with the first phase position p1 in accordance with the modulation frequency. In the case shown, this signal or the electromagnetic radiation is reflected by an object 40 and, due to the distance covered, impinges on the receiving element 22 with a second phase position p2 as a received signal S(p2) with a corresponding phase shift. In the receiving element 22, the modulation signal M(p1) mixed or demodulated with the received signal S(p2), the phase shift or the object distance d being determined from the resulting signal.

2 shows a cross section through a light transit time pixel of a photomixing detector such as that shown in FIG DE 197 04 496 A1 is known. The modulation photogates Gam, G ₀ , Gbm form the light-sensitive area of a PMD pixel. According to the voltage applied to the modulation gates Gam, G ₀ , Gbm, the photonically generated charges q are directed either to one or the other accumulation gate or integration node Ga, Gb.

In the configuration of the modulation gates, the middle modulation gate G ₀ can optionally also be dispensed with. Alternatively, such a light transit time pixel can also be designed without modulation gates, as is the case, for example, in FIG EP 1 332 594 A2 shown and described.

2 B shows a potential curve in which the charges q flow in the direction of the first integration account Ga, while the potential according to 2c allows the charge q to flow towards the second integration node Gb. The potentials are specified according to the modulation signals present. Depending on the application, the modulation frequencies are preferably in a range from 1 to 500 MHz, possibly even higher. A modulation frequency of 1 MHz, for example, results in a period of one microsecond, so that the modulation potential changes accordingly every 500 nanoseconds.

In 2a A readout unit 400 is also shown, which may already be part of a PMD time-of-flight sensor designed as CMOS or a receiving element 22. The integration nodes Ga, Gb designed as capacitors or diodes integrate the photonically generated charges over a large number of modulation periods. In a known manner, the voltage then present at the gates Ga, Gb can be tapped at high resistance, for example via the readout unit 400 . The interconnection and evaluation of the first and second integration node Ga, Gb forms a so-called A and B channel.

3 shows a time-of-flight sensor 22 known from the prior art for distance determination with a light-time-of-flight pixel 23 or a receiving surface for demodulation and determination of the phase shift of a detected light signal. The transmitter 10 and receiver 20 or their components are arranged and/or aligned with one another in such a way that the light signal Sp1, Sp2 that is sent and reflected by the object 40 can be received by the light transit time pixel 23 in a preferred distance measuring range. The beam formation is designed in such a way that the light signal Sp2 in the form of a light spot 50 impinges on the light transit time pixel 23 . The expansion area of the incident light spot 50 is preferably smaller than the area of the light transit time pixel 23.

Like in the 3 can be seen, the useful light only illuminates a small part of the photosensitive surface of the light transit time pixel 23. The largest part of the pixel is illuminated by the background light or extraneous light.

The core idea of the invention is now to adapt the light transit time pixel 23 to the specifics of the respective optical system design. The optical system design depends on various parameters, in particular the size of the sensor itself, such as the transmitter-receiver distance or focal length, the structure of the optical system, for example single-eyed or double-eyed, the type of transmitter, for example LED, laser, and other parameters.

To different device classes or different system designs with the same To allow time-of-flight sensor 22, the size of the light-time-of-flight pixel 23 must be chosen as large as possible. However, such a large light transit time pixel 23 has the disadvantage that in many optical designs an unnecessarily large amount of extraneous light is collected. This disadvantage can be remedied, for example, by means of a device-specific mechanical screen. However, the application of such a mechanical aperture is associated with considerable adjustment effort.

An electronic, “freely configurable diaphragm” according to the invention, on the other hand, enables the receiving surface to be adapted to the respective optical design without additional adjustment effort.

With the "electronic shutter" according to the invention, it is also possible to optimally adapt the active reception area of the light transit time pixel to be evaluated during operation, depending on the measurement situation, the measured distance values and/or the useful signal strength. In the case of very bright objects, for example reflections, it makes sense to reduce the active receiving area in particular in order to avoid saturation of the signal preamplifier stage. This goal can also be achieved by means of the “freely configurable aperture” according to the invention.

4 shows a solution according to the invention in which, in contrast to the prior art, the light transit time pixel 23 is divided into a plurality of reception areas 23.1-23.6. In the example shown, the light spot 50 is in the third and fourth receiving area 23.3, 23.4.

According to the invention, it is now, as in 5 shown, provided to use only the reception areas for the distance measurement, in which a useful light, so here the modulated light spot 50 can be detected. In the case shown, only the third and fourth reception areas 23.3, 23.4 would be taken into account for the distance measurement. These reception areas 23.3. 23.4. are so-called active receiving areas or active receiving areas. The first, second, fifth and sixth reception areas 23.1, .2, .5, .6 are not to be taken into account for the distance measurement and are so-called blanked-out reception areas.

It should be noted that active and blanked-out reception areas 23.n differ only in terms of whether the signals detected in this area are evaluated or not. Otherwise, both the active and the blanked-out receiving areas are supplied with a modulation signal, with the charges in the active areas being passed on to an integrator and the charges in the blanked-out receiving areas being passed on to a reject node.

If the light spot hits 50, as in 6 shown, on another area, here the second and third receiving area 23.2, 23.3, these areas would be the active areas and should be taken into account in the evaluation while the other areas are hidden.

7 shows a preferred variant of the invention of a time-of-flight sensor 23, in which, in contrast to 2 the integration nodes Ga, Gb are in the form of diode nodes Da, Db, with the n-well having a metal contact on the upper side. In order to shield the modulation voltage present at the modulation gates Yarn, G0, Gbm, the diode nodes are also surrounded by a separation gate G _sa , G _sb . The metal contact on the n-well can optionally completely cover the area of the surrounding separation gate G _sa , G _sb as light protection. However, further variants are also conceivable, in which further insulation and metal layers can be applied.

In 8th shows a plan view of the arrangement according to FIG 7 . In the example shown, three diode nodes D _a , D _b are arranged within the separation gates Gsa, Gsb, the metal contacts of which are connected to a conductor track for charge transport. The diode nodes D _a , D _b and the associated strip conductor each form a readout finger D _a1 , D _b1 , via which the charges located in the vicinity of the diode nodes D _a , D _b can be derived.

According to the invention it is provided according to the structure 8th continuously as in 9 shown as building a contiguous time-of-flight pixel 23 . In the embodiment shown, a reception area 23.n always includes two readout fingers D _an , D _bn of a channel A, B. In contrast to a conventional pixel, the reception areas 23.n are not sharply delimited, so that the readout fingers always also have charges at a reception area boundary from the adjacent detection area 23.n+1.

The detection areas are preferably designed in such a way that the modulation gates adjacent to the readout finger are preferably at the same modulation potential.

10 shows a readout circuit according to the invention for tapping the charges present at the readout fingers D _an , D _bn . The readout fingers D _an , D _bn can be connected to either an integrator 410 or a discard node 450 via a switch S.

In the illustrated case, the upper readout fingers Da1, Db1 for the A and B channels are connected to an A channel and a B channel input of the integrator 410 via the switch S1. The lower readout fingers Dan, Dbn have both the A and B channels connected to an input of discard node 450 in common. A reference voltage Vref is present at the input of the reject node, which also essentially corresponds to the voltage present at the A- and B-channel inputs of the integrator 410 . This ensures that there are no significant potential differences between the active reception areas and the blanked reception areas that are connected to the reject node.

11 shows an example of a possible switching process over time. The switches for the active reception areas are denoted by S(A, B) and the switches for the masked out areas by S(V _VK ). During a charge integration, which starts at t _{int_0.1} in the example shown, the active receiving areas are connected to the integrator 410, the blanked areas to the discard node 450.

In the integration pauses, ie between t _{int_1.1} and t _{int_0.2} , the switches S remain in their position. However, should a change in these positions be helpful for the accuracy of the following measurements during operation, this change should take place during the integration pause. Otherwise, measurement results may become incorrect due to switching during integration. The integration pause begins after the integrated signal has been sampled and ends with the removal of the reset as the beginning of a new integration.

In this pause, the integration capacitance Cint is also short-circuited via the switch RS.

A possible configuration of a time-of-flight pixel 23 according to the invention is shown in 12 shown. For the sake of clarity, the modulation gates between the readout fingers D _an , D _bn are not shown. The light transit time pixel has three reception areas 23.1, .2, .3. Four readout fingers D _an , D _bn of a channel A, B are each electrically combined as a group via a conductor track and connected to a changeover switch S _An , S _Bn , consisting of two transistors. Depending on the applied switching signal UG, UG the transistors connect the A and B channels of a receiving area 23.n either to the integrator 410 or to the reject node 450. The integration or evaluation of the charge carriers generated in the light-sensitive receiving areas 23.n thus takes place outside of the receiving areas 23.n or of the light transit time pixel 23. The combined reception areas 23.n form a common active reception area.

The device according to the invention is of course not limited to the embodiment shown, so it is conceivable that each readout finger has its own changeover switch S, so that the reception areas can be subdivided even more finely, it is also conceivable to combine more than four readout fingers.

As in the other figures 12 is only a schematic illustration, the selection fingers can be made significantly longer, for example, so that, for example, a structure according to FIG 5 can be stretched. Other dimensions are also possible.

13 shows what is known as a two-eyed optical range finder, in which the illumination 10 and the time-of-flight sensor 22 are arranged laterally offset. Due to the angular relationship between the emitted and received light, the light spot 50 changes its location on the light transit time pixel 23 depending on the object distance. This so-called triangulation behavior is typically compensated for, as in 3 shown, the light transit time pixel 23 has a sufficiently large receiving area.

According to the invention, it is provided to optimize the receiving surface with regard to an expected triangulation movement. 14 shows a time-of-flight pixel 23 according to the invention, which, as in 5 already shown, has several reception areas 23.1 ... 6. The reception areas 23.3, 23.4 illuminated by the useful light are actively used to determine the distance.

To prevent light spot 50 from leaving the preferred or active reception areas when there is a distance-dependent movement of light spot 50, reception element 22 is arranged in relation to illumination 10 in such a way that light spot 50 only moves along a longitudinal axis of reception areas 23, depending on the object distance .n moves. The extent of the reception areas 23.n is preferably optimized in such a way that the light spot 50 in the preferred measurement area does not leave a likewise preferred reception area 23.n.

15 shows a so-called single-lens optical distance measuring system in which the transmitting and receiving optics are on one axis. The light from the light source or illumination 10 is guided, for example, via a light guide 17 into a central area of the receiving optics 25 and emitted outwards in the direction of an object 40 . The light reflected from the object 40 is via the receiving optics 25 on the light runtime pixel 23 as Light spot 50 projected. The light transit time pixel 23 is constructed from an array of reception areas 23.n.

The light spot 50 with the usable light that can be evaluated is essentially in the central area of the pixel 23. The reception areas 23.1 - 23.n outside the light spot 50, shown hatched here, are not illuminated by the useful light and are hidden, i.e. connected to the reject node 450 The reception areas 23.n, which at least partially detect the light spot 50 or useful light, are connected to the integrator 410 via the switches and form a common active reception area.

The active reception areas are connected to a common signal line and are evaluated together, i.e. as a single reception area. The interconnected reception areas thus correspond to an individual pixel in terms of their electrical effect.

The procedure according to the invention thus makes it possible to adapt the geometry of the light transit time pixel 23 to an application-dependent geometry of the useful light by activating and hiding reception areas 23.n.

Dividing the pixel area into two dimensions is particularly advantageous for single-lens optical systems, i.e. for systems in which the transmitter and receiver are on the same optical axis. Here the centroid of the spot image stays in the same position on the pixel regardless of the object distance. In this case, the active detection area can preferably be restricted in both dimensions. When using a detection matrix, it can also be provided that the size of the active reception areas 23.n be adapted as a function of the detected light intensity.

Furthermore, the size of the active distance range can also be adjusted dynamically as a function of other measured values, in order to be able to counteract a system-related change in the spot image size as a function of the object distance, for example.

16 shows an embodiment for a binocular system according to FIG 13 in which the reception areas 23.n are arranged in a matrix over the light transit time pixel 23. The active receiving area for capturing the modulated light is structured like a funnel. On the one hand, this configuration takes into account the lateral migration of the light spot 50 due to the triangulation effect and a distance-dependent change in the size of the light spot 50. In the close-up range, the light spot 50 typically has the largest dimension and becomes smaller with increasing object distance, with the light spot 50 simultaneously moving from the left Near range emigrates to the far right range. A matrix-like arrangement of the detection areas 23.n now allows this fact to be taken into account and, as in 16 shown to structure the active reception areas 23.n in a funnel shape.

If distance information is available, it is also conceivable, as in 17 and 18 shown to limit the active reception areas to the respective light spot size and position and to hide the other reception areas.

Reference List

1

time-of-flight camera system

10

transmitter, lighting

12

light source

15

Transmission optics, beam shaping optics

17

light guide

20

Recipient

22

receiving element

23

time-of-flight pixels

23.n

reception areas

25

receiving optics

30

modulator

40

object

40'

Object changed location

50

light spot

50'

Light spot in the far range

400

readout unit

410

integrator

450

warp knot

i.e

object distance

ChA

Channel A

CH B

Channel B

there, db

diode node

Dan, DBn

selection finger

Gam, Gbm

modulation gates

G0

middle modulation gate

M(p1)

modulation frequency

qa, qb

charge carrier

SA1..n, SB1..n

switch

S(p1)

transmitted modulation signal

S(p2)

received modulation signal

IA, IB

Stream of integration nodes

Claims (7)

Time-of-flight sensor (22) for an optical range finder (1), with a time-of-flight pixel (23) for demodulating a received modulated light signal (Sp2), the light-time-of-flight pixel (23) having a plurality of receiving areas (23.n) arranged in a matrix with at least one readout finger (D _an , D _bn ) for an A and B channel, and a respective readout finger (D _an , D _bn ) has at least one integration node (D _a , D _b ) designed as a diode node, the light transit time pixel (23) having an integrator (410) for integrating the charges detected at the diode nodes (D _a , D _b ), and the readout fingers (D _an , D _bn ) of a channel (A, B) individually or in groups, each with an input of a switch ( _{SA1. .n} , S _B1..n ) are connected, the switch (S _A1..n ) for read fingers (D _to ) of the A channel at a first output of the switch (S _A1..n ) with an A channel Input of the integrator (410) and the switch (S _B1..n ) for the readout finger (D _bn ) of the B-channel at a first output of the switch (S _B1..n ) with a B-channel input of the integrator (410) and in that the changeover switches (S _A1..n , S _B1..n ) are connected at a second output to an input of a discard node (450), the time-of-flight sensor (22) being designed in such a way that, during operation, the changeover switches (S _{A1 ..n} , S _B1..n ) connect the readout fingers (D _an , D _bn ) either to an input of the integrator (410) or to an input of the discard node (450), wherein at a further input of the discard node (450) a Reference voltage (Vref) is present, which corresponds to the voltage present at the other A and B channel inputs of the integrator (410), the reception areas (23.n) whose readout fingers (D _an , D _bn ) being connected to the integrator ( 410) are connected, form active reception areas (23.n), and the readout fingers (D _to , D _bn ) are connected to the integrator (410) in such a way that the geometry of the combined active reception areas (23.n), a distance-dependent location - Considering the change in size of the light spot (50). Time of flight sensor (22) after claim 1 , in which the geometry of the active reception areas (23.n) connected and combined with the integrator (410) is funnel-shaped. Time of flight sensor (22) after claim 1 or 2 , which is designed in such a way that the switching of the reception areas (23.1. - 23.6) or the readout fingers (D _an , D _bn ) to the integrator (410) or reject node (450) depending on a determined distance value and/or the strength of the received signal takes place. Time of flight sensor (22) after claim 3 , in which, depending on the determined distance value, location and size of the combined reception areas (23.n), which are connected to the integrator (410), are selected such that they correspond to the expected size and position of the light spot (50). Time-of-flight sensor (22) according to one of the preceding claims, in which the time-of-flight sensor (22) is arranged in such a way that when the distance of the object (40) changes, the light spot (50) moves in the direction of a longitudinal axis (28) of one of the reception areas (23.n). Time-of-flight sensor (22) according to one of the preceding claims, in which the reject node (450) models an impedance and/or an input voltage (V _Ref ) of the integrator (410). Optical distance meter (1) with a time-of-flight sensor (22) according to one of the preceding claims, with a transmitter (10) for emitting a modulated light signal (Sp1) in the form of a light spot (50), with a modulator (30) which provides a modulation signal for the transmitter (10) and the receiver (20), wherein the transmitter (10) and the time-of-flight sensor (22) are arranged at a distance from one another.

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